Tank base

ABSTRACT

A method for the construction of an improved tank base. A tank base is constructed for protection against accidental spills and/or leaks associated with a tank battery. The improved tank base comprises at least one part of a suitable substrate, which allows for the adhesion of an elastomer such as polyurea. Polyurea is preferably applied using a spray device which yields an average coverage of about 50-80 mils, and most preferably 60 mils. If more than one substrate is used, one or more substrates can be bound together with a fastening system. Once pressure is applied in the form of weight, the fastening system can be removed, resulting in an improved tank base having at least one seam and impervious to the fluid of the tank battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/937,925, filed Jul. 24, 2020, which is a continuation of U.S.application Ser. No. 16/683,001, filed Nov. 13, 2019, which is acontinuation of U.S. application Ser. No. 15/230,890, filed Aug. 8,2016, which is a continuation of U.S. application Ser. No. 14/285,898,filed May 23, 2014, which is a continuation of U.S. application Ser. No.12/365,781, filed Feb. 4, 2009, which claims the benefit of the filingdate of, and priority to, U.S. Provisional Patent Application No.61/106,778, filed Oct. 20, 2008. Each of the above referencedapplications is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to a structural element that provides loadbearing support and the method for the production of same. Inparticular, an encapsulated polystyrene structure serves as a loadbearing material for use in protecting against accidental spills andleaks associated with any type of storage, tank, or vessel.

Description of Related Art

During the production of oil and gas from an underground well, it iscommon for water to be produced along with the oil or gas. This water,called “produced water,” is typically separated from the oil or gas atthe well site and temporarily stored in an above-ground storage tank, orAST (or combination of ASTs). The produced water varies in quality fromone well to the next, and it can have high quantities of minerals,salts, oil, gas, sand and other substances dissolved, mixed or suspendedin it. Produced water with a high concentration of impurities can becorrosive to the walls and ancillary piping of an AST and it can betoxic to the environment. A vehicle with a large storage tank attachedto it periodically travels to the well site and transfers the producedwater from the AST to the storage tank or vessel on the vehicle.

FIG. 1 illustrates an AST 100 with an input stream 18 and an outletstream 20. The flow rate of the outlet stream 20 is manipulated by wayof a valve 22. The produced water travels from the undergroundhydrocarbon bearing formation 6, up the oil or gas well bore hole 4,into what is known as a “Christmas tree” 10, which is an assembly ofvalves, pipes and fittings used to control the flow or oil and gas froma well. The water separating section 14 of the Christmas tree 10 directsthe produced water to the AST 100. Other separating sections 12 directthe oil or gas into a pipeline 16, which transports the oil or gas toother locations for further processing or sale. A manway entrance 350enables a technician to view the interior of the storage tank andinspect the tank for leaks, while the plumbing connections 380 to thestorage cavity of said tank enable pumping of the contents therein. Asseen in the side view in FIG. 1 , the manway 350 extends below thebottom of the tank.

Accidental spills or leaks can occur for a variety of reasons. Forexample, FIG. 2 illustrates the AST 100 of FIG. 1 after the producedwater has corroded the walls of the tank, creating a hole 26 in the wallof the AST. The hole 26 allows the produced water to spill or leak outof the AST 100 and onto the ground 2. In order to protect theenvironment from an accidental discharge such as the one illustrated inFIG. 2 , approved ASTs are typically required to retain any and allfluid such that contaminate are prevented from entering the environmentsurrounding the well site. Fluid accumulates within ASTs and secondarycontainment systems from multiple sources including natural andaccidental leaks or spills. ASTs usually need to have the capacity andstrength to hold at least 150% of the volume of the AST, or for an arrayof ASTs, 150% of the largest AST in the array.

Currently, protection for the tank, soil and equipment in thecontainment of the top soil involves the use of a grade band of metalfilled with pea gravel below the containment tank. The grade band metalis typically bolted together to form a base greater than the diameter ofthe containment tank it supports. The diameter of the support structure(base and pea gravel) is typically 3″ to 6″ greater than that of the ASTbeing supported and allows for the AST to sit approximately 3″ to 6″ inheight off of the floor of a secondary containment area. This allows theAST or containment tank to be at a level greater than the ground leveland aids in the slow deterioration of the tank due to any standing fluidwithin the secondary tank area, whether the fluid is natural (such asrainwater) or accidental (spills or leaks). The pea gravel currentlyused is naturally porous and allows for the absorption for any number ofcontaminants (i.e., oil, salts, acids, etc.) that come into contact withthe gravel, causing permanent contamination, which still tends to spillout of the gravel upon oversaturation. Attempts to treat or wash out thecontaminants are costly, difficult, and to-date, ineffective.

Consequently, a need exists for a more efficient, effective, andconvenient method for building an improved tank base to provide forsafer environment and green waste. There is a need for an improved tankbase, capable of being steam cleaned of any contaminants to provide moreenvironmentally friendly standards while maintaining other advantages ofa tank base and reducing costs associated with maintenance orreplacement of failing tanks. There is also a need for a tank base thatprovides for a more efficient and cost-effective means of the shipping,transporting, and installation into customer sites. Further, there is aneed for a method which keeps out moisture, preventing the proliferationof bacteria which often causes erosion of tanks from the inside out.

SUMMARY OF THE INVENTION

The present invention provides a method for the encapsulation of a corematerial, which allows for the adhesion of an elastomer such aspolyurea. In one embodiment, at least one part of a substrate such asexpanded polystyrene (EPS) is designed or shaped and subsequently coatedwith polyurea for protection and strength. Preferably, the foam materialcomprises a density of at least two pounds per cubic foot of foam weightwith an average coverage of about 50-80 mils and most preferably about60 mils polyurea. Other suitable substrates (including withoutlimitation wood, metal, concrete, paper fiber, fiberglass, fiber board,and gravel) allow for the adhesion of polyurea, which is preferablyapplied using a spray device. This allows for the protection of anabove-ground storage tank (AST) system in addition to a moreconveniently portable installation.

In a second embodiment, more than one part of a substrate is shaped asdesired or needed to fit beneath a tank. Each substrate is individuallycoated with the polyurea and the coated materials are then fastenedtogether around the outside circumferential periphery of the base andheld together under the weight of an AST. The materials comprise atleast one seam to allow for moisture to pass through such that nocorrosion of the tank is experienced as a result of any standing fluidfrom accidental spillage or natural rainwater. Once pressure is appliedin the form of weight, the fastener can be removed, resulting in animproved tank base having at least one seam and impervious to the fluidof the tank battery or within a secondary containment system. Thepolyurea-covered EPS is biodegradable and allows for steam cleaning tobe rid of contaminating hydrocarbons and green waste disposal, ifnecessary.

Other aspects, embodiments and features of the invention will becomeapparent from the following detailed description of the invention whenconsidered in conjunction with the accompanying drawings. Theaccompanying figures are schematic and are not intended to be drawn toscale. In the figures, each identical or substantially similar componentthat is illustrated in various figures is represented by a singlenumeral or notation. For purposes of clarity, not every component islabeled in every figure. Nor is every component of each embodiment ofthe invention shown where illustration is not necessary to allow thoseof ordinary skill in the art to understand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbe best understood by reference to the following detailed description ofillustrative embodiments when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of a prior art above ground storage tank at awell site.

FIG. 2 is an illustration of a prior art above ground storage tank witha hole in its wall.

FIG. 3 is an illustration of above ground storage tank situated over atank base of the present invention.

FIG. 4 is an illustration of top perspective view of one embodiment ofthe tank base of the present invention.

FIG. 5 is an illustration of a side perspective view of the embodimentof the tank base of the present invention seen in FIG. 4 .

FIG. 6 is an illustration of a side perspective view of an alternateembodiment of the tank base of the present invention.

FIG. 7 depicts a top perspective view of an alternate embodiment of thetank base of the present invention.

FIG. 8 depicts the side view of the alternate embodiment of the tankbase of the present invention illustrated in FIG. 7 .

FIG. 9 depicts an alternate embodiment of the tank base of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention involves an improved method for the constructionof a tank base for use in a secondary containment area, storagefacilities or any type of vessel. While the tank base of the presentinvention is described in terms of a secondary containment for a varyingsizes of an AST, one skilled in the art, armed with this disclosure,will recognize that the present method and its resulting tank base isapplicable to any number of secondary containment systems and vesselstorage areas. Thus, while FIG. 1 depicts a cylindrical AST with itsaxis oriented perpendicular to the ground 2, one skilled in the art,armed with this disclosure, will recognize that the claimed inventionworks equally well within secondary containment systems of varyingorientation, shape and positions relative to the ground or environmentbeing protected. Further, as will be described below, the tank base ofthe present invention can be modified or custom built to accommodate anysize and shape desired.

The exterior bottom portion of an AST is particularly susceptible todamage resulting from standing fluid when the AST is sitting directly onthe floor of a secondary containment area. As described above, currentmethods of resolving this problem involves the use of a large tank basehaving portions bolted together and filled with pea gravel, whichpermanently absorbs contaminants. Current methods are labor intensiveand require multiple parties to construct and supply the tank base.

FIG. 3 illustrates an AST 100 situated over the center portion of a tankbase 300 of the present invention. As described above, moisture fromstanding water around the edges of a tank pose a problem for themaintenance of a tank 100 and contamination of the soil beneath thetank. The manway entrance 350 is illustrated in FIG. 3 , depicting thatportion of the tank to which access is granted for maintaining the tank,and is shown to extend now to the top of the tank base of the presentinvention. Thus, the containment base allows the tank 100 and plumbing380 to be situated higher up from the ground, providing easier accessthrough the manway 350. Preferably, any flat portion on the tank base isaligned with the manway entrance 350 to allow for ease of entry. In theembodiment seen in FIGS. 3 and 4 , the tank base comprises three parts320, 340 and 360 and two seams 310 in between each piece; however, asfew seams as possible are preferable and if desired, one solid base withno seams is also possible. For ease of transfer and construction, thebase is typically comprised of at least two parts or substratespositioned adjacent and secured to one another, creating an outerperiphery around which a fastening system is employed to bind thesubstrates together.

As used herein, the term “suitable substrate” is used synonymously with“substrate” and is meant to include without limitation, concrete, metal,EPS, wood, concrete, paper fiber, fiberglass, fiber board, and gravel orany other substrate appropriate for the adhesion of a polyurea elastomercoating. Polyurea is an elastomer derived from the reaction between anisocyanate component and a resin blend component. Polyurea suitable forthe present invention is available from Sherwin Williams under the nameENVIROPLASTIC® AR200HD or Versaflex under the name FSS 50DM. Currently,landfills and dike systems utilize secondary containments comprising EPSencapsulated with earth. Without being bounded by theory, it is believedthat the present invention provides an improved tank base in part due tothe high compressive strength of EPS in combination with the highadhesion rate and strength of polyurea, which helps encapsulate thepolystyrene and keeps it from flaking off and failing under the weightof a the tank. While Applicants describe the present invention in termsof EPS due to its environmentally friendly nature and powerful designelements, other substrates having a compressive strength are alsopossible. EPS is 100% recyclable and in some parts of the world iscurrently already being recycled at higher levels than either glass oraluminum. Used polystyrene is biodegradable and has no impact on theenvironment even in landfill sites or in incinerators, nor does itcontain substances that could pollute the air or soil. Further, themanufacture of EPS solutions does not release hydrosoluable substancesthat could contaminate ground water supplies. Suitable EPS materials arecommercially available.

The method by which the present invention is constructed will now beexplained. The first step is to design the substrates to be encapsulatedas support for a tank battery or in a secondary containment system. Asused herein, the designing step is meant to include the cutting, shapingor forming of the substrates into custom shapes or sizes to be used withvarying sizes of tanks or within a given containment area. At least onesubstrate is designed to customer requirements and according to the sizeand diameter required for the tank battery. As depicted best in FIG. 4 ,the measurements x and y can vary to any number depending on thesecondary containment system or AST to be supported. In test runs, atank weighing approximately 110 thousand pounds called for EPS having afoam density of 2 pounds per cubic foot of foam weight, ranging fromabout 3 to 12 inches in height. In addition, the overall diameter of oneor more substrates when lying side by side was about 10 to 18 feet indiameter during successful test runs. One skilled in the art, armed withthis disclosure, will recognize that one or more substrates can be usedin accordance with the present invention. For example, a solid base canbe used and alternatively, two solid halves of a base can be placedadjacent to one another and tied together to form a base with at leastone seam, which allows for the passage of water to prevent corrosion ofthe tank. Further, it can be recognized that the foam density can beincreased to accommodate more than 100 thousand pounds and to providethe load bearing support needed for the present invention.

The next step involves independently encapsulating each substrate with apolyurea elastomer. Once formed to the necessary specifications orsizes, each substrate is individually coated with polyurea forprotection and strength. Preferably, the application is performed usingspecialized equipment that uses high temperatures and high pressures formixing directly in an impingement mix spray gun. In one embodiment, thepolyurea coating is independently applied using a spray device operatingat a temperature of approximately 165 degrees Fahrenheit and a pressureof approximately 1800 pounds per square inch (psi) to encapsulate eachsubstrate. The average coverage of polyurea will be about 50-80 mils,and more preferably about 60 mils coverage. However, one skilled in theart, armed with this disclosure, will recognize that other coverages arealso possible depending on the desired compressive strength of the tankbase and the required application.

The third step in creating the improved tank containment base of thepresent invention involves binding the coated substrates together at thewell site. The substrates are positioned adjacent to one another andbound together with a fastening system. Simultaneously or subsequently,the substrates can be aligned appropriately as discussed above, with themanway entrance aligned with a flat section of the tank base. Whenaligning the base, the plumbing features of the tank is also be takeninto account such that a flat edge is aligned with the manway entranceand plumbing. In test runs, a 45 foot nylon strap with a cam buckle wasused to secure the coated substrates around the outer periphery of theedges and hold the pieces together until the pressure from the weight ofthe tank is applied. Once properly aligned, the AST is placed on thetank base and the fastening system may be removed, if desired, or maystay in place as the discretion of the owner. The polyurea coating ofthe tank base is impervious to the fluid of the AST and will not allowfor the contamination of the substrate or deterioration of the AST. Thecoating also allows for ease of cleaning as the material can now besteamed to extract out any hydrocarbon resins. This also allows for theenvironmentally safe disposal of the base if necessary.

As seen in FIGS. 4 through 9 , the independent nature of the substratesforms seams 310 in between the substrates. It is desirable to have asfew seams as possible. FIGS. 5 and 6 illustrate side views of the basesand the corresponding seams possible with the present invention.Straight seams depicted in FIG. 5 allow for any moisture from rainwater,for example, to pass through so as to prevent corrosion of the tank fromstanding water effects. Interlocking seams seen in FIG. 6 also allow formoisture to seep away from the bottom of the tank but also allow foranother embodiment in which to piece or hold together the substrates. Itis noteworthy that the secondary containment system should be as levelas possible with only a slight gradient to allow fluid to “pool” at oneend for removal (i.e. pumping) requirements. Alternatively, FIGS. 7 and8 depict an alternate embodiment wherein the center substrate portion340 is slightly raised above the height of side substrate portions 320and 360. This allows for pooling to occur along either side of the base,rather than in the center of the tank. FIG. 7 further depicts the use offunnels 370 to aid in dispersing fluids away from underneath the tankfor release into specific areas within the secondary containment system.FIG. 8 depicts another embodiment of the present invention, comprising adifferent shape.

While the invention has been particularly described with reference topreferred embodiments, it will be understood by those skilled in the artthat various changes in form and detail may be made therein withoutdeparting from the spirit and scope of the invention. For example, oneskilled in the art, armed with this disclosure, will recognize that avariety of shapes and dimensions are possible with the present inventionand can be tailor made according to the needs of a secondary containmentsystem and/or the weight to be applied to the base. Further, theinvention can be used in and around any area having highly corrosive orhazardous material and with any vessel or storage container. The termsand expressions employed herein have been used as terms of descriptionand not of limitation; and thus, there is no intent of excludingequivalents, but on the contrary it is intended to cover any and allequivalents that may be employed without departing from the spirit andscope of the invention.

What is claimed is:
 1. A tank base, comprising: a first part,comprising: a first foam substrate having a first thickness; and a firstelastomer disposed on an outer surface of the first foam substrate; asecond part positioned adjacent to the first part, the second partcomprising: a second foam substrate having a second thickness; and asecond elastomer disposed on an outer surface of the second foamsubstrate; and a seam formed between the first and second parts to allowfor fluid to disperse, via the first seam, if the tank base provides aload-bearing support for an above-ground storage tank.
 2. The tank baseof claim 1, wherein: each of the first and second parts comprises acurved edge portion; and each of the respective curved edge portions ofthe first and second parts forms part of an outer periphery of the tankbase such that the outer periphery is generally circular or oblong inshape.
 3. The tank base of claim 1, wherein the first and second partsare shaped such that the first seam interlocks the first part with thesecond part.
 4. The tank base of claim 1, wherein the first foamsubstrate and the second foam substrate each comprise a foam materialhaving a density independently of at least about 2 pounds per cubicfoot.
 5. The tank base of claim 4, wherein the foam material comprisesexpanded polystyrene, and wherein the first elastomer and the secondelastomer each comprise a polyurea.
 6. The tank base of claim 1, whereinthe first elastomer and the second elastomer each have a thickness of atleast about 50 mils, wherein the first thickness of the first foamsubstrate and the second thickness of the second foam substrate areindependently at least about 3 inches.
 7. The tank base of claim 1,wherein the above-ground storage tank has a weight of more than 100thousand pounds.
 8. The tank base of claim 1, wherein the firstelastomer encapsulates the first foam substrate and the second elastomerencapsulates the second foam substrate.
 9. The tank base of claim 1,wherein the fluid is a liquid.
 10. The tank base of claim 9, wherein theliquid is water.
 11. The tank base of claim 1, wherein the tank basecomprises no more than two seams.
 12. A secondary containment system,comprising: a floor; and a tank base disposed on the floor, the tankbase comprising: a first part, comprising: a first substrate having afirst thickness; and a first elastomer disposed on an outer surface ofthe first substrate; a second part positioned adjacent to the firstpart, the second part comprising: a second substrate having a secondthickness; and a second elastomer disposed on an outer surface of thesecond substrate; a first seam formed between the first and secondparts; and an above-ground storage tank disposed on the tank base;wherein the first seam allows for fluid to disperse away from the bottomof the above-ground storage tank and onto the floor, via the first seam,when the tank base provides the load-bearing support for theabove-ground storage tank.
 13. The secondary containment system of claim12, wherein the first and second parts are shaped such that the firstseam interlocks the first part with the second part.
 14. The secondarycontainment system of claim 12, wherein the first substrate and thesecond substrate comprise a foam material having a density of at leastabout 2 pounds per cubic foot.
 15. The secondary containment system ofclaim 14, wherein the foam material comprises expanded polystyrene. 16.The secondary containment system of claim 14, wherein the firstelastomer and the second elastomer independently comprise a polyurea.17. The secondary containment system of claim 13, wherein: the firstelastomer and the second elastomer each have a thickness of at leastabout 50 mils, the first thickness and the second thickness are each atleast about 3 inches, and at least one of the first and second partsdefines a dimension sized to accommodate the outer circumference of theabove-ground storage tank and to provide the load-bearing support forthe above-ground storage tank, the dimension extending in a directionthat is perpendicular to each of the respective first and secondthicknesses of the first and second substrates.
 18. The secondarycontainment system of claim 13, wherein the above-ground storage tankhas a weight of more than 100 thousand pounds.
 19. The secondarycontainment system of claim 13, wherein the tank base comprises no morethan two seams.
 20. A secondary containment system, comprising: a floor;a tank base, and the tank base comprising: a first part, comprising: afirst substrate having a first thickness; and a first elastomer disposedon an outer surface of the first substrate; a second part positionedadjacent to the first part, the second part comprising: a secondsubstrate having a second thickness; and a second elastomer disposed onan outer surface of the second substrate; and a first seam formedbetween the first and second parts; and an above-ground storage tankdisposed on the tank base, the above-ground storage tank in fluidcommunication with an underground hydrocarbon bearing formation via awell bore hole.